This invention relates to methods and apparatus for the manufacture of microstructures. In particular, but not exclusively, this invention relates to the methods and apparatus for the manufacturer of semiconductor devices, and other microstructures, such methods involving the use of masking techniques. This invention also relates to novel microstructures, in particular, but not exclusively, novel semiconductor devices particularly those which may be manufactured by the use of masking techniques. This invention is of particular, although not exclusive, relevance to the field of thin film transistors, particularly transparent thin film transistors.
The manufacture of microstructures, particularly semiconductor devices, has transformed modern society. The highly flexible and useful products which may be made from these devices are now an integral part of modern life, and there is a continuing need to manufacture such devices more cost effectively, both to lower the cost of current products and to open up new markets.
Typically, at present, semiconductor based microstructures are manufactured by an etching process. A mask is applied to a multi-layered silicon structure, various chemical etching techniques are used to remove layers of the structure, preferentially layers which are not protected by the mask. Multiple masks may be used in the manufacture of more complex devices, with each mask being chemically removed from the silicon multilayer structure.
However, there are disadvantages with many current fabrication processes. In particular, it is difficult to manufacture low cost, relatively simple, microstructures cost effectively. This is because typical fabrication processes rely on economies of scale, with the result that it is more cost effective to manufacture devices with a degree of redundancy but that are suitable for many applications, than application-specific devices, which have, inherently, smaller markets. The need for economies of scale also means that it is difficult to mix and match manufacturing processes cost-effectively.
There is a need to introduce flexibility into the manufacturing process of such microstructure.
Present methods are particularly disadvantageous when it comes to the manufacture of flexible micro-structures, or the manufacture of micro-structures on a flexible substrate, such as in the manufacture of flexible displays. The films which make up the multi-layer structure may break or become degraded (with respect to operational lifetime and performance and storage life) if over-flexed.